1. Field of the Invention
The present invention generally relates to three-dimensional micro-machined devices and more particularly to a micro-machined mirror apparatus having multiple axes of rotation and discrete positioning.
2. Description of the Related Art
Micro-machined devices have gained widespread use in a variety of applications in recent years. One such application is the use of such devices in optical applications in which a micro-machined mirror structure is used as an optical switch to deflect an incident light beam to redirect the light beam in a plurality of directions.
The typical MEMS mirror used as an optical switch includes a micro-machined mirror structures that can be deflected by applying electrical energy to one or more electrodes. The energized electrodes provide a force on the mirror thereby inducing an angular change in the surface plane of the mirror.
It is desirable to have a mirror surface with two axes of angular (i.e. rotational) freedom in these optical switches. Some typical devices provide such freedom by providing a gimbaled coupling between the mirror and a mirror support structure, then providing a gimbaled coupling between the mirror support structure and a second support structure. Other known devices include a pedestal-type mirror structure.
While these typical devices provide the desired degrees of freedom, they suffer from several disadvantages. These devices provide only analog movement. This movement is a continuous sweeping movement from one angular position to another angular position. As such, any induced mechanical shock during operation may move the mirror thereby disrupting the operation. Moreover, accurate positioning using electrical energy is very difficult. Thus it is desirable to provide a planar mirror surface with multiple axes of rotation, and providing digital positioning. Digital positioning as used herein is defined as one or more discrete planar positions including known angular relationships to a beginning or reference planar angle.
Another problem with the typical optical switch is that they are relatively difficult to manufacture. MEMS devices are three-dimensional structures. MEMS optical switches typically require at least two stacked layers having electrodes and electrode contacts passing from one layer to the next. The conventional process includes non-planar etching and dicing techniques that increase manufacturing time and reduce the reliability of the final product. Thus, it is desirable to provide a product manufactured using planar processes for etching, bonding and electrode traversal of multiple tiered devices.